1. Field of the Invention
The present invention relates to a fuel cell suitable for a vehicle, a boat, a portable generator or a small generator for household use and, more particularly, to a method for measuring water content of the fuel cell.
2. Related Art
In a fuel cell with a short water content, the electrolyte membrane has high resistance because it is dry. Therefore the fuel cell outputs a lower voltage in comparison with a fuel cell with the proper water content, even when the same amount of current is outputted. On the other hand, in a fuel cell with an excessive water content, the water in the fuel cell prevents the gas from diffusing toward the reaction site. Therefore the fuel cell with an excessive water content also outputs a lower voltage in comparison with a fuel cell with the proper water content.
Accordingly, the water content of the fuel cell should be adjusted to a proper value in order that the fuel cell operates efficiently. However, no method for measuring the water content of the fuel cell is known, and therefore shortage or excess of the water content cannot be detected. Accordingly the water content of the fuel cell cannot be appropriately adjusted.